I posted here some time ago. This time I'm begging!

I've go oil pressure problems on my 99 Ram 1500 4x4. During the first 5 minutes of driving I have normal oil pressure. As the temp increases, oil pressure decreases from 60psi to about 20psi in about 10 minutes. At that time, if I put the engine under a load the pressure drops to zero. If I rev the engine to 3000+RPM the pressure drops to zero, cold or hot. All readings are with a mechanical gauge.

I've cleaned and flushed the engine, installed a HV Melling pump, new pickup and replaced the main and rod end bearings. I've screamed and threw tools, tried thicker oil and everything I can think of. I've removed the valve covers and intake and verified oil flow with a drill / pump primer. Everything looks perfect, but it doesn't work!

Any ideas? Does anyone know where I can find an oil circuit drawing for a 5.2L Dodge, or know the path the oil takes?

 

have you downloaded the manual? found in the dodge info thread (merry christmas reference) posted at the top of the forum.

it could be possible that you have a spun cam bearing... are there any noieses coming from the motor?

 

Nope. No noise what so ever. EXCEPT, when the pressure drops to zero I hear something from the oil pan that sounds like the pump cavitating.....I soft whine..... then I have a little oil pressure again (maybe 10psi). There's no valvetrain noise at all, ever.

I'll try to d/l the manual now...

 

I can't find the manual.... ????

 

here ya go https://dodgeforum.com/m_340929/tm.htm

 

Fantastic! Thanks guy!

I know what I'll be doing tonight.

 

could one of your return galleys be plugged and the oils not making it back into the pan fast enough?

 

That's a great idea...... but I checked that when I pulled the intake off. I run the pump with the engine open, there were no problems at all.

I dunno how stupid this sounds, but I think I may have a chunk of oil goo or something after the oil pump / filter in the main galley. It's the only thing that makes sense ( I think ).

I bought a couple cans of engine flush. I'm not sure just how I'm going to use it yet. The directions say 1 can for 5 minutes at idle.... change the oil. I was wondering if I could pump 4 quarts of the stuff through my engine using the drill / priming shaft. Then chase it with fresh oil. Just a thought.

 

****, you don't need that engine flush BS. Drank about a quart of oil out of the crankcase and then pour either a quart of diesel or kerosene in there and drive around for an hour. Then, drank the pan and add fresh oil with a fresh filter. Also, I would run 4 quarts of oil with 1 quart of Marvel Mystery Oil.

The reason I say to stay away from those "engine flush" products is that they're nothing more than diesel or kerosene with some additives. Save your money. Since the price of diesel is so high, I recommend kerosene. Plus, if you're worried about kerosene, just remember that it is the #1 ingredient of WD-40 and is a derivative of oil.

 

I recently installed a brand new Melling oil pump, Melling oil pump screen, and Melling oil pump shaft when I installed my new engine and it also had some oil pressure at first then went down to zero. Upon pulling the NEW oil pump out of the engine we discovered that it was bad and was itself the cause of the low oil pressure problem. I installed a second Melling pump from a different parts store ( to insure a different production run ) and no longer have the issue. Oil pressure is perfect.

it's possible your pump is also bad. Only costs you about $40 for another pump and a hour or two of your time to look into this. When you pull the pump there are a couple things you should do.

1) from under the engine look into all ofthe oil passages you can see into looking for any build up of gunk. If you do not see any, then there probably is not any elsewhere in the engine.
2) again clean the screen and verify there are no blockages in it.
3) When you install the new pump be extra careful to fully seat the pump against the block. A mis-aligned oil pump will crack the pump housing and not allow the pump to keep the oil pressure where it should. ( I have seen this issue with the Magnum engines ).
4) If you have one available, you should remove the oil pressure sending unit and temporarily replace it with a mechanical oil pressure gauge. If you obtain good pressure when running with this gauge, reinstall your sending unit, reset your PCM because the check engine light will come on, and the nrun the engine again. If the pressure is not correct, you probably have a bad sending unit. If you replace the sending unit and still have an incorrect pressure then the gauge in your dash is probably the culprit.

Since it sounds like you have the ability to run the oil through the engine with the priming shaft you could test the new pump or if you feel OK about your install, just start the engine with a close eye on the oil pressure gauge.

Hope this helps.